Circuit breaker



June 28, 1949. E. v. SUNDT 2,474,752

CIRCUIT BREAKER Filed May 26, 1945 2 Sheets-Sheet l 49 mia xmm (INVENTOR. I EDWARD V Swvnr. BY

ATTORNEY.

June 28, 1949. E. v. SUNDT 2,474,762

CIRCUIT BREAKER Filed May 26, 1945 2 Sheets-Sheet 2 INVENTOR. [pm-mp l. Suma-r.

Patented June 28, 1949 UNITED STATES;

CIRCUIT BREAKER.

Edward V. Sundt, Arcadia, Calif.

Application May 26, 1945, Serial No. 596,053

8 Claims. (01. 200 416)" This invention relates to electrical apparatus; and more especially to a circuit breaker to be placed in an ordinary fuse block for protecting. a circuit in the nature of a fuse.

An object of the invention is to provide a novel circuit breaker constructed for mounting in an ordinary fuse block so as to be interchangea'ble with a cartridge typefuse.

Another object of the invention is to provide a circuit breaker that is interchangeable with fuses, and having a timela'g characteristic which is several times that of the ordinary fuse, yet comparing favorably with fuses that have an abnormal time'lag used for the protection of motors;

A; further object of the invention is to provide a circuit breaker or the character described having a time lag characteristic which is desirable for ordinary overloads, however having a high speed break effective under short circuit conditions.

An additional object of the invention is to provide a circuit breaker which is interchangeable A further object of the invention is to provide" a circuit breaker having a bimetal' release element directly associated with the reset parts, and so constructed: as to provide a double break in series with the load circuit.

A further object of the invention is to provide a circuit breaker of the character'described, providing a trip -free action by removal of the circuit breaker from the receptacle or fuse block.

Another object of the invention is to provide a circuit breaker as described wherein non-tripfree action is provided by a cover which is pivoteclv on the contact elements which are inserted: in the fuse clips, the cover being swingable only by removal of the breaker from the fuse clips.

An additional object of the invention is to provide a novel circuit breaker interchangeable with fuses, and one whichcanbe inserted into the fuse block in only one way due to the shape and construction of the circuit breaker housing.

Other objects and advantages will appear andbe brought out more fully in the following specifi- 2; cation considered with. reference to the accompan'yin'g' drawings throughout which like parts are designated by like numerals.

In the drawings:

Figure 1 is a side elevation view of a circuit breaker embodying my invention, shown secured to the clips of a fuse blo'ck.

Figure 2 is an end view of the same.

Figure 3 is a view similar to Figure 2 showing. the trip-free swingable element in released position.

Figure 4 is an enlarged View in central sectio'ri of thecircuit breaker embodying my invention.

Figure 5 is a cross-section view of the same taken along the line 5--5" of Figure 4.

Figure 6- is a view similar to Figure 5', the section being taken along the" line 6-6 of Figure 4.

Figure 7 is a View similar to Figure 4' showing the reset part in disconnected position.

Figure 3 is aperspective viewshowing the bus bar and b'imetal elements separate from the assembly.

The present invention relates generally tothe art of' protecting electrical circuits against excessive load current and short circuit conditions,v in which art the conventional protective devices comprise fuses or circuit breakers, and such de-' vices have been generally designed With more specific applicability to either the fuse type or circuit breaker typeof circuit protection. Fuses generally have somewhat limited characteristics, as' for instance, fuses customarily have a com"- p'aratively short time" lag characteristic. Fuses, however, have the advantage of comparatively" low cost, but have the disadvantageof requiring: manualreplacement often requiring appreciable time for this manipulation.

On the-otherhand circuitb'rea'kers', while customarilydesig'ned' for circuits-operating at higher" current loads, areusually 'm'orecomplicated structures requiring:electro-m'agnets or solenoids, however, circuit breakers 'have a number ofa'dvantage's" which include quick operation withshort time lag characteristics, together with" the fact that circuit breakers can": be reset very quickly and do not require replacement 01 parts.

The present invention" contemplates overcom ing; the objections and disadvantages of fuses and circuit breakers by theprovisionof adevicewhich has both fuse and! circuitv breaker characteristics; The circuit breaker ofi this: invention, while de scribed: as such; nevertheless. differs from the com ventionalcircuit brea'kerini not having magnetic windings or movable" amma'turea. butpro'vi'des a. switch element which is arranged open the: circuit upon a predetermined load condition by 3 utilizing a bimetal element, and to be reset to operative condition when the abnormal load condition has been corrected.

One of the features of the present invention is the provision of means which require the removal of the device from the circuit in order to effect the reset operation, so that the device is in condition to protect the circuit when replaced therein, even if the abnormal condition still exists, and thus protects the circuit and the person who is making the resetting, thus avoiding all possibility of causing an injurious burn, if the device were attempted to be replaced under a short circuit condition, if not in condition for immediately protecting the circuit. A further important feature of the invention is the provision of a circuit breaker device constructed in the form and with some of the dimensions of a conventional cartridge fuse and adapted to be used in a conventional cartridge type fuse block.

Referring more particularly to the drawings, I show the circuit breaker device of this invention in connection with a conventional fuse block In having a pair of spaced fuse clips I l suitably secured thereto and having circuit terminal screws or equivalent devices l2, the clips each comprising complementary resilient clip members or jaws l3.

The circuit breaker itself comprises a body I4 of suitable insulating material, such as a molded plastic, and having a pair of cylindrical end boss portions l5 and an extension base portion IS. The body has a generally flat top portion I! formed with a rectangular aperture l8 and has a pair of extension portions Ila for a purpose which will become apparent hereinafter. Body [4 forms a hollow chamber [9 for the reception of the bimetal and bus bar parts and the reset mechanism.

End bosses l5 are each provided with a cap electrode which is generally cylindrical and has the dimensions of the ferrule or corresponding cap electrode of a cartridge fuse having the load carrying capacity of the circuit breaker which would replace it. Each cap 20 has a bearing pin 2| suitably secured thereto and extending there from for mounting the shield, to be more fully disclosed hereinafter.

I show a pair of bus bar assemblies, of which one assembly 22 comprises a contact plate member 23 and an angular extension 24 having a flanged tip 25 suitably connected as by soldering for electrical engagement with cap 20. Plate 23 has a cut-out portion 26 forming a notch. The other bus bar assembly 28 comprises a contact plate 29 having a cut-out notch 33 opposite notch 26 and is formed with an extension 3| having a contact tip 32 secured to the other cap electrode 20. Plate 29 and extension 3| are connected by a, bimetal element 33 having a leg 34 secured to plate 29 and a leg 35 connected to a flanged por tion of plate extension 31'. Bimetal element 33 has a flanged upper edge portion 36 forming a stop for engagement with the reset button.

The reset mechanism comprises an assembly 31 including a jumper bar 38 which is generally U- shaped in section and provided with a rectangular opening 39 through which extends the shank 43 of a reset button 40 formed with a rectangular sectioned stem 4i having a shoulder 42 and a shank 43 as mentioned. A coiled compression contact spring 44 is positioned between jumper bar 38 and the bottom of the body chamber and is centered between and spaced from plates 23 and 29 by shank 43 which extends into the coils of the spring.

A snap spring 45 is positioned between jumper bar 38 and shoulder 42 and has shank 43 extending therethrough. Stem 4| of button 40 has a pair of bosses 46 forming abutments which are formed with cam surfaces 41, one of which bosses is adapted for engagement with stop 36 of bimetal element 33 by which button 40 is held in set position, as shown in Figure 4, in which position jumper bar 38 will be held firmly in contact with bus bar contact plates 23 and 29 forming the electrical interconnection therebetween.

A flexible button shield 48 is provided and positioned as shown, being secured to top I! by a suitable marginal seal, the shield being preferably of a flexible plastic material, and transparent so that the position of the button may be seen at all times. If desired, jumper bar 38 may be provided with auxiliary contacts 49 of silver or an alloy which will not become pitted or corroded by the electrical arcs formed when the contacts are separated.

I show a button shield 50 which may be formed of a suitable, preferably transparent, plastic material having flanged end portions 5|, each formed with a bearing bore 52, for hearing mounting on bearing pins 2|, the construction of shield 50 being such that when the circuit breaker is secured to the fuse clips l3, shield 50 will be in centered position extending over the top of body [4 and button 40, and flanged ends 5| are positioned partially between clips 13.

The operation of the invention should be clear from the foregoing description. Assuming the circuit breaker is in set position, as shown in Figures 4 and 5, the path of electric current is from the right hand cap electrode 20 through bus bar extension 24, contact plate 23, jumper bar 38, contact plate 29, bimetal element 33 and bus bar extension 3! to the other cap electrode 20. Upon a current passing through these parts exceeding the predetermined amount for tripping the circuit breaker, bimetal element 36 will be heated and flexed outwardly so that stop 36 releases itself from abutment 46, whereupon spring 44 will push jumper bar 38 up, thus breaking the contact with plates 23 and 29, and this movement also pushes push button 40 up within shield 48 being aided in this movement by spring 45. When it is desired to reset the circuit breaker upon the overload condition being relieved push button 40 can be pressed manually so that jumper bar 38 reconnects plates 23 and 29 and stop 36 engages abutment 46, thus holding the button 40 and jumper bar 38 in a position shown in Fi ures 4 and 5.

Figures 1 to 6 show the guard or shield 50 which serves as a trip-free mechanism, whereby the circuit breaker must be removed from the fuse clips H to permit the guard to be rotated to an angular position, as shown in Figure 3, in order to reset the reset mechanism including jumper bar 38 and push button 49, it being apparent that guard 5i! is held against rotation over push button s53 inasmuch as the flanged ends of the guard are positioned between the pairs of fuse clip jaws it. If desired the circuit breaker may be used, as shown in Figure 7, without the shield or guard 56*, in which case the circuit breaker will operate as a non--trip--free circuit breaker.

Although I have herein shown and described my invention in what I have conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope of my invention, which is not to be limited to the details disclosed herein but is to be accorded the full scope of the claims so as to embrace any and all equivalent devices and systems.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

1. A circuit breaker comprising; a hollow body having spaced external electrodes, a pair of spaced bus bars connected to said electrodes, one of said bus bars having a bimetallic 'polrtion formed with a stop, a jumper bar for interconnecting said bus bars, and means mounting said jumper bar for releasing the bus bars connection upon a predetermined current passing through said bus bars, said means including a push button extending through a wall of said body having a stop engaging abutment, a flexible shield over the external end portion of said push button and having its marginal edge portions sealed to said body and a guard over the shield pivotally secured upon the body.

2. A circuit breaker comprising; a body having spaced electrodes adapted to be attached to the terminals of a fuse clip, a pair of spaced bus bars connected to said electrodes, one of said bus bars having a bimetallic portion formed with a stop, a jumper bar having a pressure contact with both said bus bars, a push button, spring pressed abutment means mounting said jumper bar for releasing the bus bars connection upon a predetermined current passing through said bus bars, and a pivoted guard for said push button.

3. A circuit breaker comprising; a body having spaced electrodes adapted in operative position to be atached to the terminals of a fuse clip, a pair of spaced bus bars connected to said electrodes, one of said bus bars havin a bimetallic portion formed with a stop, a jumper bar for interconnecting said bus bars, a push button, spring pressed abutment means mounting said jumper bar for releasing the bus bars connection upon a predetermined current passing through said bus bars, and a guard for said push button pivotally mounted upon an axis directed between said fuse clips adapted to be positioned over said push button when the circuit breaker is held in operative position, said means having a stop abutment adapted to be held normally by said stop and released therefrom when said bimetallic portion is thermally retracted.

4. A circuit breaker comprising; a body havin spaced electrodes adapted in operative position to be attached to the terminals of a fuse clip and in inoperative position to be released therefrom, a pair of spaced bus bars connected to said electrodes, one of said bus bars having a bimetallic portion formed with a stop, a jumper bar for interconnecting said bus bars, spring pressed stop abutment means mounting said jumper bar for releasing the bus bars connection upon a predetermined current passing through said bus bars, a reset push button for the stop abutment and a pivoted guard for said push button adapted to be positioned over said push button when the circuit breaker is in an operative position, said guard being pivotable away from said push button when the circuit breaker is in an inoperative position.

5. A circuit breaker comprising; a body having spaced electrodes adapted to be attached to the terminals of a fuse clip, a pair of spaced bus bars connected to said electrodes, one of said bus bars having a bimetallic portion formed with a stop, a jumper bar for interconnecting said bus bars,

a push button, spring pressed stop abutment means mounting said jumper bar for releasing the bus bars connection upon a predetermined current passing through said bus bars and a guard for said push button pivotally mounted on said electrodes.

6. A circuit breaker comprising; a body having a pair of spaced electrodes adapted to be attached to the terminals of a fuse clip, a fuse clip having a pair of spaced resilient terminals, a pair of spaced bus bars connected to said electrodes, one of said bus bars having a bimetallic portion formed with a stop, a jumper bar for interconnecting said bus bars, a push button, spring pressed stop abutment means mounting said jumper bar for releasin the bus bars connection upon a predetermined current passing through said bus bars and a guard for said push button pivotally mounted on said electrodes, said guard having portions extending into the terminal elements of said fuse clip when the circuit breaker is secured to the fuse clip, whereby to prevent resetting of the circuit breaker while attached to the fuse clip.

7. A circuit breaker comprising a body, a fuse clip having spaced resilient terminals, electrodes adapted to be releasably engaged with said terminals, a bimetallic circuit breaking mechanism assembled with said body, a reset button cooperabie with said mechanism and a guard having in one position a portion contiguous with the reset button preventive of manual access thereto, and end portions pivotally attached to the body in positions within the terminals of the fuse clips adapted to resist pivotal movement of the guard to another position away from the rest button except under circumstances wherein the electrodes are removed from the terminals.

8. A circuit breaker comprising a body, a fuse clip having spaced resilient terminals, electrodes adapted to be releasably engaged with said terminals, a bimetallic circuit breaking mechanism assembled with said body a reset button cooperable with said mechanism, a transparent flexible button shield on the body enclosing the button, and a guard having in one position a portion contiguous with the flexible button shield preventive of manual access thereto, and end portions pivotally attached to the body in positions .vithin the terminals of the fuse clips adapted to resist pivotal movement of the guard to another position away from the flexible button shield except under circumstances wherein the electrodes are removed from the terminals.

E. V. SUNDT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 450,292 Johnston Apr. 14, 1891 1,359,298 Wadsworth et al. Nov. 16, 1920 1,614,169 Aichele Jan. 11, 1927 1,614,223 Aichele Jan. 11, 1927 1,688,006 Duisenberg Oct. 16, 1928 1,704,379 Aichele Mar. 5, 1929 1,706,518 Blough Mar. 26, 1929 1,772,291 Ruppel Aug. 5, 1930 2,348,393 Krieger May 9, 1944 

